V-erbB oncogene

The v-erbB oncogene acts to expand a pool of highly mitotic, undifferentiated erythroid precursor cells, but these are poorly tumorigenic, because they differentiate at high rates into postmitotic, end-stage red cells. Another potential oncogene, v-erbA, blocks differentiation of erythroid precursors but creates no tumors because it is unable to provide the mitogenic impetus needed to expand the pool of stem... 

The avian v-erbB oncogene and oncogene both have sequences homologous to that of the gene for the receptor for fhe 53-residue epidermal growth factor The corresponding cellular c-erbB... 

The oncogene v-erbB, unlike c-erbB, codes for a shortened form of the EGF receptor protein. Usually the binding of EGF is required to turn on the tyrosine kinase activity of the EGF receptor protein, the one coded by c-erbB. However, the tyrosine kinase activity of the receptor derived from v-erbB is switched on permanently, even in the absence of EGF. The uncontrolled grqwth characteristic of cancer cells results. 

Several cancer cell types are characterized by expressing a truncated EGF receptor. The related viral oncogene, V-er B, also encodes a truncated receptor which lacks most of the extracellular domain (the EGF receptor is also known as C-erbB). Mutant receptors that display inappropriate constitutive activity can lead to cellular transformation, due to the continuous generation of mitogenic signal. 

AEV-strain ES4 contains erbA and erbB. v-erbA is weakly oncogenic it transforms erythocyte cells in vitro but not in vivo. It is able to enhance the transforming efficiency of erbB in vivo. ErbA shows homology with steroid hormone receptors, suggesting that they may be derived from a common primordial gene (Krust et al, 1986). c-Erb is able to bind tri-iodothyronine with an affinity (Kd 0.2-0.3nM) similar to that of the thyroid hormone receptor, which it closely resembles. By contrast, v-Erb is defective in binding thyroid hormone, because of mutations in the binding domain (Vennstrom Damm, 1988). 

The human cancer antigene R (HuR) translocates in tumor cells from the nucleus into the cytoplasm to stabilize cyclins in uninterrupted cell divisions to force the overexpression of ERBB-2 in prostate cancer cells (c-erb v-erb avian erythroblastic leukemia retrovims oncogene EGF-R) [670]. K usually used for lysine. 

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